Ultimately, the Jena scientists believe they have also settled a hundred-year-old debate about the cause of cellular contractions. Nickel's team was able to show that the inner and outer surfaces - and therefore the epithelial cells, so-called pinacozytes - cause the strong body contractions of the sponges.

'Although the 3-D volumetric analysis is widely known and used in the technical sciences, it has rarely been used in zoology - in spite of its enormous information potential.' 'A key feature of our approach is the use of 3-D data for measuring the volume and surface of our sponges,' says Nickel. Using this technique, the Jena scientists, in co-operation with the Helmholtz-Zentrum Gesthacht at the Deutsches Elektronen Synchrotron Hamburg, were able to compare and visualize the 3-D structure of contracted and expanded sponges. In their paper, the researchers described how they generated three-dimensional (3-D) images, with the help of synchrotron radiation-based X-ray microtomography. In a new study published in the Journal of Experimental Biology, the evolutionary biologists are offering new answers to this question.

The scientists from the Institute of Systematic Zoology and Evolutionary Biology are especially interested in the question of which evolutionary forerunners did muscle cells derive from. Michael Nickel of Friedrich Schiller University Jena (Germany) is looking into movement without muscles. A group of scientists headed by associate professor Dr.

Does a sponge move